Paper documents are often promptly discarded after being read. Although paper is relatively inexpensive, the quantity of discarded paper documents is enormous and the disposal of these discarded paper documents raises significant cost and environmental issues. In addition, it would be desirable that paper documents can be reusable, to minimize cost and environmental issues.
Photochromic paper, also known as erasable paper, provides an imaging medium that can be reused many times to transiently store images and documents. For example, photochromic paper employs photochromic materials to provide an imaging medium for containing desired images. Typically, photochromic materials can undergo reversible or irreversible photoinduced color changes in the photochromic containing imaging layer. In addition, the reversible photoinduced color changes enable image-writing and image-erasure of photochromic paper in sequence on the same paper. For example, an ultraviolet (UV) light source can be used for inducing image-writing, while a combination of heat and a visible light source can be used for inducing image-erasure. An inkless erasable imaging formulation is the subject of U.S. patent application Ser. No. 12/206,136 filed Sep. 8, 2008 and titled “Inkless Reimageable Printing Paper and Method” which is commonly assigned with the present application to Xerox Corp., and is incorporated in its entirety herein by reference. For brevity, in the rest of the disclosure, a document printed on erasable paper can be referred to as an “erasable paper document,” and depending on the context, can refer to both the electronic and printed form.
The erasable paper can start to irreversibly fade over time. As such, erasable paper users or customers may not be able to use or see an erasable paper document once it has undergone a certain amount of fading. Further, erasable paper users or customers may be reluctant to use photochromic paper technology for fear that the erasable paper's content may not be recoverable if the erasable paper fades too much. There is no known method to prevent further fading of erasable paper or to bring back contrast to a fading erasable paper document. Therefore, it may be desirable to have systems and methods for retrieving erasable paper documents. It particular, it may be desirable to have systems and methods for using identification codes on rendered documents for the purpose of re-rendering erasable paper documents that have experienced fading.